The invention relates to a method of processing acidic Fe-containing solutions, in particular spent (discarded) pickling solutions, by means of liquid/liquid extraction with organic ion exchangers.
A method of processing spent treatment liquids containg Fe ions for materials containing metals or ores by liquid-Liquid extraction is known from EP-A 0 058 148. This method is directed to the recovery of inorganic acids free of metal ions and consists in first of all liberating the inorganic acids bound to the iron ions by means of a water-insoluble, liquid cation exchanger (for instance acidic phosphoric acid esters such as diethyl hexyl phosphate or dibutyl phosphate) binding the Fe ions. The free acids are subsequently extracted from the aqueous solution by adding an organic adduct-forming agent TBP (tributyl phosphate), DBBP (dibutyl benzyl phosphate), TOP (trioctyl phosphate, TOPO (trioctyl phosphine oxide) and the adducts are finally cleaved again, affording the pure acids.
Solutions of this type accumulate in an industrial scale and the problem posed consisted in providing a method permitting the processing of these solutions with a view to their content in Zn.